Re: [Qemu-trivial] [PATCH] hw/i386/kvmvapic: Remove dead code in patch_hypercalls()

[Jan Kiszka]

On 2017-01-09 18:05, Peter Maydell wrote:
> The patch_hypercalls() function sets up a 'patches'
> variable and checks it at the end of the function, but
> never modifies it in the middle. Remove this dead code,
> which seems to have been present since the function was
> added in commit e5ad936b0fd7 in 2012.
> 
> (Spotted by Coverity: CID 1005581.)
> 
> Signed-off-by: Peter Maydell <address@hidden>
> ---
> Perhaps this was unintentionally retained debug code?
> It's not clear to me why the ROM should be required to
> have exactly zero or two hypercalls in it. In any case
> we've been fine without checking the patch count for
> five years :-)
> 
> CC'd Jan as original code author just in case he remembers.
> ---
>  hw/i386/kvmvapic.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/hw/i386/kvmvapic.c b/hw/i386/kvmvapic.c
> index b30d1b9..418dba1 100644
> --- a/hw/i386/kvmvapic.c
> +++ b/hw/i386/kvmvapic.c
> @@ -534,7 +534,6 @@ static int patch_hypercalls(VAPICROMState *s)
>      uint8_t alternates[2];
>      const uint8_t *pattern;
>      const uint8_t *patch;
> -    int patches = 0;
>      off_t pos;
>      uint8_t *rom;
>  
> @@ -565,11 +564,6 @@ static int patch_hypercalls(VAPICROMState *s)
>      }
>  
>      g_free(rom);
> -
> -    if (patches != 0 && patches != 2) {
> -        return -1;
> -    }
> -
>      return 0;
>  }
>  
> 

Hmm, it looked that dead from day #1 on, and I cannot blame it on the
qemu-kvm version as well. Maybe the idea was to count the number of
patches we applied and have this as cross-check. But then I forgot to
count. It's probably safer to bury this code than to try starting to
count to 2 now.

Acked-by: Jan Kiszka <address@hidden>

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